[Haskell-beginners] What's this [f| data |] ??

Hi. I'm trying to get into haskell in my free time. I have already covered some syntax, but there's plenty to do yet, and when I'm consulting other people's stuff, I find lots of unknown constructs to me, which turns harder to lookup for, due to the very "symbolic" nature of Haskell. For instance, on this http://www.yesodweb.com/blog/2012/04/yesod-js-todo they have a few constructs like this: |mkYesod "App" [parseRoutes| /HomeR GET /todoTodosR GET PUT /todo/#TodoId TodoR GET DELETE |]| It seems that the inline text is going to be fed to parseRoutes. How does that constructs work (links?)? I already know list comprehensions which appear to be related with this. Thanks.